Recent observations suggest that El Niño–Southern Oscillation (ENSO) impacts basal melting of West Antarctic ice shelves, yet sparse ocean observations limit our understanding of the associated processes. Here we investigate how ENSO events modulate subsurface West Antarctic shelf temperatures using high-resolution global ocean-sea ice model simulations. During El Niño, the subsurface shelf warming between 150 m and the shelf bottom can be up to 0.5°C in front of ice shelves. This warming arises from a weaker Amundsen Sea Low (ASL) and weaker coastal easterlies that reduce on-shelf Ekman transport of cold surface waters, enabling enhanced transport of warm Circumpolar Deep Water (CDW) onto the shelf. A largely opposite response occurs during La Niña, with a stronger ASL and stronger Ekman transport that results in less cross-shelf CDW transport and cooling in the subsurface. These findings have implications for interpreting basal melting on interannual to decadal time-scales in West Antarctica.

中文翻译：

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与厄尔尼诺-南方涛动有关的西南极大陆架地下变暖

最近的观测表明，厄尔尼诺-南方涛动（ENSO）影响了南极西部冰架的基础融化，但稀疏的海洋观测限制了我们对相关过程的理解。在这里，我们利用高分辨率全球海洋-海冰模型模拟研究 ENSO 事件如何调节西南极大陆架地下温度。厄尔尼诺现象期间，冰架前150 m至陆架底部之间的地下陆架升温可达0.5°C。这种变暖是由于阿蒙森低气压 (ASL) 减弱和沿海东风减弱造成的，这减少了埃克曼冷地表水在陆架上的输送，从而增强了温暖的环极深水 (CDW) 向陆架的输送。拉尼娜期间发生的反应很大程度上相反，ASL 更强，Ekman 输运更强，导致跨陆架 CDW 输运和地下冷却减少。这些发现对于解释西南极洲年际至年代际时间尺度的基底融化具有重要意义。